use a fresh stack when loading Errno.pm etc.

Stops 'use vars qw($!)' in lib/vars.t segfaulting.
(This can be reduced to 'my $sym = "!"; *$sym = \$$sym')

p4raw-id: //depot/perl@30577

1 files changed, 2 insertions, 1 deletions

diff --git a/gv.c b/gv.c
index 6c664db956..26308bb273 100644
--- a/gv.c
+++ b/gv.c
@@ -697,11 +697,12 @@ S_require_tie_mod(pTHX_ GV *gv, const char *varpv, SV* namesv, const char *methp
 				  so save it. For the moment it's always
 				  a single char. */
 	dSP;
-	PUTBACK;
 	ENTER;
 	if ( flags & 1 )
 	    save_scalar(gv);
+	PUSHSTACKi(PERLSI_MAGIC);
 	Perl_load_module(aTHX_ PERL_LOADMOD_NOIMPORT, module, NULL);
+	POPSTACK;
 	LEAVE;
 	SPAGAIN;
 	stash = gv_stashsv(namesv, 0);